Background. HIV care has been rapidly decentralized in high-prevalence countries like Zimbabwe, in the drive to expand access to antiretroviral therapy (ART) and to achieve viral suppression in people living with HIV/AIDS (PLWH).1,2 Optimising adherence to simple affordable regimens is especially critical in settings where third-line ART is barely available. Depression in Zimbabwe, like elsewhere, is common in PLWH3 and a key barrier to ART adherence.4 There is a dearth of interventions for depression and poor ART adherence which are feasible for non-specialists to deliver. These facts underscore the public health significance of focusing on those with depression and a detectable viral load receiving ART regimens. Preliminary work. We have conducted extensive preliminary work to evaluate the cultural appropriateness and feasibility of a stepped care, task-shifted intervention for treating depression and non-adherence in Zimbabwe. Using available lay adherence counselors, this intervention links with the existing Zimbabwean HIV care pathway. We 1) culturally adapted the Life-Steps adherence intervention through qualitative studies and tested it in 100 PLWH,5 2) developed a combined depression-adherence intervention called TENDAI (meaning ?thankful? in the Shona language) through integrating the adapted adherence intervention with Problem-Solving Therapy for depression (a simple culturally-acceptable treatment for depression used in Zimbabwe)6 and 3) successfully completed an open trial and then a pilot randomized trial of TENDAI.7 Together, these studies show feasibility, acceptability and potential beneficial effects on depression, adherence, and HIV viral suppression. Our combined US, UK and Zimbabwean consortium bring together a history of successful trials in HIV and depression.8-10 Our proposal is strongly endorsed by the Ministry of Health AIDS and TB Unit. Design: we propose a two-arm effectiveness RCT of the TENDAI intervention in HIV clinics in rural Zimbabwe in 290 people on ART (first, second or third line treatment) with a detectable viral load (=> 1000 viral RNA copies) and clinically significant depression. The TENDAI intervention will be compared to Enhanced Usual Care (EUC). Primary outcomes at 12 months (Aim 1) include proportion of HIV viral suppression in each condition, adherence to ART (assessed electronically and by ART detection in Dried Blood Spot), and depression (assessed via a locally validated questionnaire by an independent evaluator). We will also test (Aim 2) moderators (sex, depression severity) of the treatment effect, and examine changes in adherence and depression as mediators of the effect on viral suppression. Through collecting resource utilization and cost data we will examine the cost-effectiveness of our novel treatment compared to EUC on reduced depression and, potentially, on better HIV outcomes (Aim 3). If successful, the RCT results will enable us to recommend a strategy for adherence counseling and depression care locally and in the east and southern African region.